C.pneumoniae is now a well accepted cause of community-acquired respiratory disease. It is now proposed to expand the investigation of the role of C.pneumoniae in chronic and systemic infection, specifically atherosclerosis and chronic respiratory diseases. The association of C.pneumoniae infection and cardiovascular disease will be further investigated in studies evaluating: accelerated atherosclerosis in young persons; the presence of C.pneumoniae in ruptured coronary artery atheroma; the relationship of C.pneumoniae antibody to C-reactive protein and these measurements to cardiovascular events 7-10 years after serum measurements; to retrospectively determine the effect of prior antibiotic treatment on occurrence of cardiovascular events; to simultaneously measure antibody against C.pneumoniae, Herpes simplex virus, CMV, and Helicobacter pylori in persons with CAD; and the relationship of antibody to C.pneumoniae and ischemic cerebral infarction. The relationship of C.pneumoniae and chronic respiratory disease including sarcoidosis, COPD, asthma, and lung cancer will also be investigated. In addition, they will also investigate asymptomatic pharyngeal infection in children and adolescents and the relationship to seroconversion and transmission. As stated above, most of these studies rely on serology, several will attempt to identify C.pneumoniae in tissue by culture, PCR, and/or immunohistochemical staining.